Collaborative Research: Fast and efficient phase-change photonics using low-dimensional materials

University Of Maryland, College Park, College Park MD

Investigators

Abstract

This project aims to demonstrate an active optical device that simultaneously exploits the unique properties of phase-change and two-dimensional materials. Active optical devices are currently achieved with platforms that require a constant power supply, which is energy inefficient in optical applications with sporadic modulation, such as light-based data storage. The reversible yet stable optical response of phase-change materials has been explored as a solution to this problem, given that their stable states allow for zero-static power operation. These properties and their nanofabrication versatility have resulted in unprecedented device performances in applications ranging from imaging to on-chip optical computing. However, such applications rely on phase-change materials optimized for the near-infrared spectrum (where telecommunications take place). In contrast, several other classical and quantum technologies would benefit from modulation closer to the visible spectrum. This project aims to fill this gap by developing novel phase-change material and their control mechanism, microheaters, that are transparent in the visible and compatible with any substrate. To create the microheater, this project will explore the unique properties of two-dimensional materials such as graphene, which is transparent and allows for fast heating and cooling speeds. This project’s fast and efficient platform based on phase-change and two-dimensional materials will be broadly applicable to technologies such as metasurfaces, optical filters, novel computing architectures, and reconfigurable (quantum) photonics. This project aims to explore the use of microheaters composed of low-dimensional materials as a method for high-speed and efficient control of low-loss reconfigurable phase-change photonic devices for platforms beyond silicon. Phase-change materials, such as Ge2Sb2Te5, Sb2Se3, etc., are particularly promising for reconfigurable optical devices owing to their fast, dramatic, non-volatile, and reversible change in refractive index. Experimental demonstrations of reconfigurable smart windows, metasurfaces, and photonic devices for memory and computing have reignited interest in these alloys. However, work exploring electrical control over optical phase-change devices has been limited to optically opaque platforms for wavelengths <1.2µm, not compatible with photonic platforms beyond silicon, and have slow heating and cooling rates which limit their switching speed and energy efficiency. Therefore, to fill these critical needs, this project aims to 1) develop new solutions for controlling phase-change materials using a substrate-agnostic platform with ultrafast 2D microheaters, 2) improve the optical transparency, speed, and endurance by developing new phase-change alloys and systematically studying their failure mechanisms, and 3) demonstrate efficient and reliable waveguide integration. The project outcomes will have immediate relevance in the fast-growing field of nonvolatile photonics, including free-space applications such as metasurfaces and optical filters and photonic integrated circuits for telecom, neuromorphic computing, and quantum processing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.